Cutting a Clean Hole in Thin Aluminum

[RCS]

Looking for the tool and the right advice on cutting a nice clean small diameter round hole in a thin aluminum panel that is already mounted in place. I need to cut a 1/2" and 3/4" hole and I don't want to mangle the panel. Surely there must be a tool and technique for doing this??? Any help is very much appreciated!

[bookmaker]

Use a step drill. They don't chatter like a normal twist bit.
Also known as a uni-bit

Also back up the aluminum up on a 2x4 or something when drilling.

[CarlOrton]

absolutely use the step/uni drill! You'll wonder how you got by without it all these years!

[lathropdad]

You can get step drills for 1/2 inch maximum diameter and 3/4 inch maximum diameter. I would suggest that you start with the 1/2 inch and then go to the 3/4 size for holes larger than 1/2 inch.

[Mike Switzer]

I prefer a Greenlee tool for making round holes in sheetmetal, but they are expensive & you need the correct size die. You wouldn't want to buy one for one hole, but most professional electricians & some sheetmetal shops have them. Some electrical supply houses will rent one.

[bookmaker]

Mike's solution is obviously the best route, especially for larger holes. Give a step bit a try on some scrap. They are reasonable cost. I have several in various combinations.

[RCS]

Makes perfect sense... a step drill is on my shopping list. Thanks for the quick and helpful feedback! --Rob

[Carbiener]

Tool named Rotabroach is good. Also woodworking spade bit that has a "tooth" at each end. I use Irwin brand, makes clean hole that just needs deburring.

[Tralika]

I agree with the previous responses, I have several step drills and they work pretty well. For large holes the Greenlee tools are best. The cleanest holes can be made with the RotaCut tools. I've used them before and they work better than a step drill. The holes come out perfect but like the Greenlee it's fairly expensive for something a home builder won't use very often. Also you can count on everyone wanting to borrow the RotaCut or Greenlee when word gets out that you have one.

https://www.hougen.com/cutters/sheet-metal-hole-cutters/Rotacut-sheet-metal-hole-cutters.html

[Fokker Builder]

Step drill and plywood work table